Patent GB-195703-A (GB)
Title: Improvements in and relating to automatic tapping, drilling and like machines
IPC: B23G1/16
Filed: 1921-12-09
Abstract: 195,703. Withers, J. S., (Gaterman Manufacturing Co., W.). Dec. 9, 1921. Tapping.-Relates to machines for drilling, tapping &c. which when the tool meets with undue resistance are automatically reversed and consists in providing means for restarting such machines in the operative direction after a predetermined amount of reversal. The reversal and subsequent restarting in the operative direction may be effected by electromagnetic means. The tool-spindle 4 has keyed to it a disc 17 which is driven from a gear 12 by means of a spring 23, Fig. 2, adjustable by a nut. The gear 12 carries a stop 21, through which passes a rod 20 adjustably secured to a slotted arm on the disc 17. The gear 12 is driven by a pinion 27 keyed to a shaft 28 on which are loosely mounted direct and reverse driving belt-pulleys, 31, 32, respectively. These pulleys have internal teeth which can be engaged by rods 37, 38 actuated by a T-shaped piece 41, pivoted to a head 34 secured by screws 36 to the shaft 28 and having one limb 43 projecting through a slot in the shaft 28 to engage between a rod 47 and a spring-pressed ball 46. The other end of the rod 47 engages a cross-pin 49 carried by a sleeve 50, which is moved to the right in Fig. 1 by the armatures 55 when the electromagnet 53 is energized. The armature carries a contact 57 which engages a contact 58 when the magnet is energized. When the magnet is deenergized the spring 48 presses the parts into the positions shown in Fig. 1, in which the reversing pulley 32 is in engagement with its pin 38. The spindle 4 is fed by a toothed sleeve 6 gearing with a pinion which is rotated by a hand lever 9, carrying the main switch 80, 81 actuated by the lever 79. The gear 12 has a boss 11 rotating on a bearing 10, forming a part of the standard 1, and an outer flange 13 which with a fixed plate 14 forms a casing. On the under side of the gear 12 are secured two contact-rings 59, 60 with which engage brushes 61, 62 having terminals 63 for the attachment of leads 85, 84, Fig. 4. The boss 11 of the gear 12 is surrounded by a spring ring 64, having a finger 65, which when the spindle 4 is rotating in the forward direction engages an adjustable stop 66 so that the spring ring 64 is opened and the boss 11 rotates freely within it. When, however, the spindle is reversed, the finger 65 engages a switch lever 68 and makes contact at 69, 70, closing the circuit through 84, 87, Fig. 4. The lead 83, Fig. 4, is connected to some electric source and when the main switch 80, 81 is closed, the current flows by the lead 84 to the brush 62, ring 60, the eprang arm 76 and ring 59 to the! brush 61, and by lead 85, contacts 57, 58, and lead 86 to the magnet 53 and return lead 82. Should the tool meet with abnormal resistance, owing to the compression of the spring 23 the spindle 4 lags behind the gear 12 and the arm 78 frees the spring arm 76, so that contact is broken at 59, 61, and the magnet is de-energized the spring 48 then pushes the parts into the positions shown in Fig. 1 and the shaft 28 and tool spindle are driven by the pulley in the reverse direction until the arm 65 closes the circuit at 69, 70 so that the magnet is again energized to actuate the clutch and throw the forward pulley into gear at the same time closing the main circuit at 57, 58. The distance through which the spindle 4 is reversed is determined by adjusting the stop 66 by means of a spring lever 72 having a detent to fit recesses 74. In starting the machine from rest. it is driven in the reverse direction until the magnet is energized.